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Abstract:

A system for providing cooling to at least one cylinder of an engine is
disclosed. The system comprises at least one coolant jacket in a cylinder
head arranged on an inlet side of a cylinder and at least one coolant
jacket in the cylinder head arranged on an outlet side of the cylinder.
The outlet-side coolant jacket may be part of a water cooling circuit,
while the inlet-side coolant jacket may be part of oil circuit.

Claims:

1. An internal combustion engine, comprising: at least one cylinder, each
cylinder having an outlet opening on an outlet side for discharging
exhaust gases and an inlet opening on an inlet side for receiving fresh
air; at least one cylinder head; and a liquid cooling device comprising
at least two coolant jackets integrated in the cylinder head, wherein at
least one coolant jacket is arranged on the inlet side of the at least
one cylinder and at least one coolant jacket is arranged on the outlet
side of the at least one cylinder, the at least two coolant jackets being
separate from one another and belonging to different coolant circuits.

2. The internal combustion of engine of claim 1, further comprising: a
cooling water circuit comprising the at least one coolant jacket arranged
on the inlet side; and an oil circuit comprising the at least one coolant
jacket arranged on the outlet side.

3. The internal combustion of engine of claim 2, wherein the cooling
water circuit does not comprise an inlet-side coolant jacket.

4. The internal combustion engine of claim 2, wherein the at least one
cylinder head is connected, at an assembly end side, to a cylinder block
which serves as an upper crankcase half for holding a crankshaft in at
least two bearings and which, at a side facing away from the cylinder
head, is connected to an oil pan which serves as a lower crankcase half
and which is provided for collecting and storing engine oil, with a pump
being provided for feeding the engine oil via a supply line to at least
one oil consumer within the oil circuit.

5. The internal combustion engine of claim 4, wherein the supply line
opens out into a main oil gallery from which ducts lead to the at least
two bearings of the crankshaft in order to supply the at least two
bearings with engine oil.

6. The internal combustion engine of claim 5, wherein, upstream of the
main oil gallery, the supply line leads through the cylinder head.

7. The internal combustion engine of claim 5, wherein, downstream of the
pump, the supply line of the oil circuit firstly leads through the
cylinder head before said supply line enters into the cylinder block.

8. The internal combustion engine of claim 1, wherein the cylinder head
is connected, at an assembly end side, to a cylinder block which, to form
a liquid cooling arrangement, has at least one coolant jacket.

9. The internal combustion engine of claim 8, wherein the at least one
coolant jacket of the cylinder block belongs to the cooling water
circuit.

10. The internal combustion engine of claim 8, wherein the at least one
coolant jacket of the cylinder block belongs to the oil circuit.

11. The internal combustion engine of claim 8, wherein the at least one
coolant jacket of the cylinder block is arranged upstream of the at least
one coolant jacket of the cylinder head.

12. The internal combustion engine of claim 1, further comprising a
cylinder block connected to the at least one cylinder head at an assembly
end side of the cylinder head and an intake line connected to each inlet
opening, wherein the at least one inlet-side coolant jacket is arranged
between the assembly end side and the at least one intake line.

13. The internal combustion engine of claim 1, further comprising a
cylinder block connected to the at least one cylinder head at an assembly
end side of the cylinder head and an exhaust line connected to each
outlet opening, wherein the at least one outlet-side coolant jacket is
arranged between the assembly end side and the at least one exhaust line.

14. The internal combustion engine of claim 1, further comprising a
cylinder block connected to the at least one cylinder head at an assembly
end side of the cylinder head and an exhaust line connected to each
outlet opening, wherein at least two outlet-side coolant jackets are
provided, with a lower coolant jacket being arranged between the assembly
end side and the at least one exhaust line, and with an upper coolant
jacket being arranged on that side of the at least one exhaust line which
is situated opposite the lower coolant jacket.

15. The internal combustion engine of claim 1, further comprising at
least two cylinders in which an exhaust line is connected to each outlet
opening, wherein the exhaust lines of at least two cylinders merge to
form an overall exhaust line within the cylinder head, so as to form an
integrated exhaust manifold.

16. A method of cooling an engine comprising: routing water through a
first coolant jacket arranged on an outlet side of at least one cylinder
of the engine; and routing oil through a second coolant jacket arranged
on an inlet side of the at least one cylinder.

17. The method of claim 15, further comprising routing the oil from a
pump to the second coolant jacket, the second coolant jacket leading to a
main engine oil gallery.

18. The method of claim 15, further comprising routing water through a
third coolant jacket arranged on the outlet side of the at least one
cylinder.

19. A thermal control system for an internal combustion engine,
comprising: a water circuit comprising a first coolant jacket integrated
into a cylinder head on an outlet side of at least one cylinder; and an
oil circuit comprising a second coolant jacket integrated into the
cylinder head on an inlet side of the at least one cylinder.

20. The system of claim 18, further comprising an oil pump configured to
pump oil from an oil pan to the second coolant jacket, the second coolant
jacket comprising an outlet coupled to a supply line for supplying the
oil to a main engine oil gallery.

Description:

RELATED APPLICATIONS

[0001] This application claims priority to European Patent Application No.
10161879.1 filed on May 4, 2010, the entire contents of which being
incorporated herein by reference.

FIELD

[0002] The present disclosure relates to systems and methods for providing
engine cooling.

BACKGROUND AND SUMMARY

[0003] A main engine oil gallery may be provided in an engine to supply
engine components such as a camshaft and crankshaft with lubricating oil.
In order to reduce oil viscosity and thus lower the energy required to
pump the oil, engines may be provided with systems to heat the oil. For
example, an external heater may be provided to heat the oil in the oil
gallery. However, the external heater itself requires energy to function
and therefore contributes to overall fuel usage in the engine, lowering
fuel economy. In other concepts, the engine oil which is heated during
operation is stored in an insulated container and utilized on demand, for
example in the event of a re-start of the internal combustion engine. A
disadvantage of this approach is that the oil which is heated during
operation cannot be kept at a high temperature indefinitely, and it is
therefore generally necessary to heat the oil during the operation of the
internal combustion engine. Additionally, both an external heating device
and also an insulated container result in an additional installation
space requirement in the engine bay, and are detrimental to the
attainment of the densest possible packaging of the drive unit.

[0004] Further, engine combustion cylinders may be provided with
mechanisms to dissipate excess heat produced during combustion. However,
the cooling may not extract more heat from the internal combustion engine
than is absolutely necessary, because the extraction of heat or the
extracted amount of heat has an influence on the efficiency of the
internal combustion engine. In some engines, more than one quarter of the
energy used is dissipated to the coolant, that is to say generally to the
cooling water, of the liquid cooling arrangement and is dissipated,
unused, to the environment.

[0005] The inventors herein have recognized the above mentioned issues and
have developed a solution to at least partly address them. Accordingly,
an internal combustion engine is provided. The engine comprises at least
one cylinder, each cylinder having an outlet opening on an outlet side
for discharging exhaust gases and an inlet opening on an inlet side for
receiving fresh air, at least one cylinder head, and a liquid cooling
device comprising at least two coolant jackets integrated in the cylinder
head, wherein at least one coolant jacket is arranged on the inlet side
of the at least one cylinder and at least one coolant jacket is arranged
on the outlet side of the at least one cylinder, the at least two coolant
jackets being separate from one another and belonging to different
coolant circuits.

[0006] For example, the coolant jacket arranged on the inlet side may
belong to an oil coolant circuit while the coolant jacket arranged on the
outlet side may belong to a water coolant circuit. In this manner, engine
oil may be rapidly heated via heat transfer through the inlet side
coolant circuit. Additionally, as water has a higher heat capacity than
oil, the water coolant circuit may be able to provide a higher level of
cooling to the outlet side of the cylinder than the oil coolant circuit
provides to the inlet side of the cylinder. Because the inlet side of the
cylinder may not release as much as heat as the outlet side, an
appropriate amount of cooling can be tailored to each cylinder side,
reducing excess cooling and conserving energy.

[0007] The above advantages and other advantages, and features of the
present description will be readily apparent from the following Detailed
Description when taken alone or in connection with the accompanying
drawings.

[0008] It should be understood that the summary above is provided to
introduce in simplified form a selection of concepts that are further
described in the detailed description. It is not meant to identify key or
essential features of the claimed subject matter, the scope of which is
defined uniquely by the claims that follow the detailed description.
Furthermore, the claimed subject matter is not limited to implementations
that solve any disadvantages noted above or in any part of this
disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 schematically shows a cylinder of an internal combustion
engine according to an embodiment of the present disclosure.

[0010]FIG. 2 schematically shows a cylinder of an internal combustion
engine according to another embodiment of the present disclosure.

[0013]FIG. 5 schematically shows a side view of the example sand cores of
FIG. 4.

[0014] FIG. 6 is a flow chart illustrating a method for cooling an engine
according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

[0015] An internal combustion engine is used as a drive for motor
vehicles. Within the context of the present disclosure, the expression
"internal combustion engine" encompasses diesel engines and
spark-ignition engines and also hybrid internal combustion engines, that
is to say internal combustion engines which are operated using a hybrid
combustion process.

[0016]FIG. 1 is a schematic diagram showing one cylinder of a
multi-cylinder engine 10, which may be included in a propulsion system of
an automobile. The cylinder 16 has a cylinder head 12 and a cylinder
block 14 which are connected to one another at their assembly end sides
so as to form a combustion chamber.

[0017] Combustion chamber (i.e. cylinder) 16 of engine 10 may include
combustion chamber walls 18 with piston 20 positioned therein. Piston 20
may be coupled to crankshaft 22 so that reciprocating motion of the
piston is translated into rotational motion of the crankshaft. Crankshaft
22 may be coupled to at least one drive wheel of a vehicle via an
intermediate transmission system. Further, a starter motor may be coupled
to crankshaft 22 via a flywheel to enable a starting operation of engine
10.

[0019] During operation, each cylinder within engine 10 typically
undergoes a four stroke cycle: the cycle includes the intake stroke,
compression stroke, expansion stroke, and exhaust stroke. During the
intake stroke, generally, the exhaust valve 34 closes and intake valve 32
opens. Air is introduced into combustion chamber 16 via intake passage
24, and piston 20 moves to the bottom of the cylinder so as to increase
the volume within combustion chamber 16. The position at which piston 20
is near the bottom of the cylinder and at the end of its stroke (e.g.
when combustion chamber 16 is at its largest volume) is typically
referred to by those of skill in the art as bottom dead center (BDC).
During the compression stroke, intake valve 32 and exhaust valve 34 are
closed. Piston 20 moves toward the cylinder head so as to compress the
air within combustion chamber 16. The point at which piston 20 is at the
end of its stroke and closest to the cylinder head (e.g. when combustion
chamber 16 is at its smallest volume) is typically referred to by those
of skill in the art as top dead center (TDC). In a process hereinafter
referred to as injection, fuel is introduced into the combustion chamber.
In a process hereinafter referred to as ignition, the injected fuel is
ignited by known ignition means such as a spark plug (not shown),
resulting in combustion. During the expansion stroke, the expanding gases
push piston 16 back to BDC. Crankshaft 22 converts piston movement into a
rotational torque of the rotary shaft. Finally, during the exhaust
stroke, the exhaust valve 34 opens to release the combusted air-fuel
mixture to exhaust passage 26 and the piston returns to TDC. Note that
the above is shown merely as an example, and that intake and exhaust
valve opening and/or closing timings may vary, such as to provide
positive or negative valve overlap, late intake valve closing, or various
other examples.

[0020] A valve actuating device depicted in FIG. 1 comprises two camshafts
36 and 38, on which a multiplicity of cams 40, 42 are arranged. A basic
distinction is made between an underlying camshaft and an overhead
camshaft. This relates to the parting plane, that is to say assembly
surface, between the cylinder head and cylinder block. If the camshaft is
arranged above said assembly surface, it is an overhead camshaft,
otherwise it is an underlying camshaft. Overhead camshafts are preferably
mounted in the cylinder head, and are depicted in FIG. 1.

[0021] The cylinder head 12 is connected, at an assembly end side, to a
cylinder block 14 which serves as an upper half of a crankcase 44 for
holding the crankshaft 22 in at least two bearings, one of which is
depicted as crankshaft bearing 46. At the side facing away from the
cylinder head 12, the cylinder block 14 is connected to an oil pan 48
which serves as a lower crankcase half and which is provided for
collecting and storing engine oil. The oil pan 48 serves as a heat
exchanger for reducing the oil temperature when the internal combustion
engine 10 has warmed up. Here, the oil situated in the oil pan 48 is
cooled by means of heat conduction and convection by means of an air flow
conducted past the outer side.

[0022] A pump 50 is provided for feeding the engine oil via a supply line
52 to a main engine oil gallery 64. The engine oil gallery 64 may be
arranged above or below the crankshaft 22 in the crankcase 44 or else
integrated into the crankshaft 22. Ducts lead from the main oil gallery
to feed at least one consumer within an oil circuit 60. Example oil
consumers include bearings of the camshaft and crankshaft, hydraulically
actuable camshaft adjusters or other valve drive components, etc. In
contrast, according to other systems, the supply line leads from the pump
through the cylinder block to the camshaft receptacle, and in so doing,
passes the so-called main oil gallery.

[0023] In previous systems, the pump which is provided is itself provided
with engine oil originating from an oil pan via a suction line which
leads from the oil pan to the pump, and said pump ensures an adequately
high feed flow, that is to say an adequately high feed volume, and an
adequately high oil pressure in the supply system, that is to say oil
circuit, in particular in the main oil gallery.

[0024] The cylinder head 12 and the cylinder block 14 are thermally highly
loaded components which require cooling, and the thermal management of
the internal combustion engine is dominated primarily by said cooling,
that is to say the configuration of the internal combustion engine is
determined by the cooling and not by other thermal management issues,
such as fast heating of the engine oil.

[0025] The heat released during the combustion by the exothermic, chemical
conversion of the fuel is dissipated partially to the cylinder head 12
and cylinder block 14 via the walls 18 which delimit the combustion
chamber and partially to the adjacent components and the environment via
the exhaust-gas flow. To keep the thermal loading of the cylinder head 12
within limits, a part of the heat flow introduced into the cylinder head
12 may be extracted from the cylinder head again. The amount of heat
dissipated to the environment from the surface of the internal combustion
engine by radiation and heat conduction is not adequate for efficient
cooling, for which reason cooling of the cylinder head is generally
effected in a targeted manner by means of forced convection.

[0026] The cylinder head 12 of the internal combustion engine according to
the disclosure has two coolant circuits which are independent of one
another and which comprise in each case at least one coolant jacket, and
which in particular can be and preferably are operated with different
coolants. One coolant jacket 54 is located on an inlet side of the
cylinder, that is, the coolant jacket is integrated into the cylinder
head 12 at the side of the cylinder that is adjacent to and surrounding
the intake passage 24. Another coolant jacket 56 is located on an outlet
side of the cylinder, that is, the coolant jacket 56 is integrated into
the cylinder head 12 at the side of the cylinder that is adjacent to and
surrounding the exhaust passage 26. The cylinder head may further have an
upper outlet side coolant jacket 58. The first, lower coolant jacket 54
may be arranged between the exhaust passage 26 and the assembly end side
of the cylinder head 12, and the upper coolant jacket 58, may be arranged
on that side of the exhaust passage 26 which is situated opposite the
lower coolant jacket 56.

[0027] This arrangement leaves free an adequate amount of installation
space on that side of the cylinder head 12 which faces away from the
block 14, for example for the arrangement of a camshaft receptacle, and
leads to a compact design.

[0028] In some embodiments, at least one connection may be provided
between the upper and lower coolant jackets 56, 58 to permit passage of a
coolant (shown in FIG. 3). The at least one connection is preferably
situated on that side of the coolant jackets which face away from the
cylinders.

[0029] As a result of the provision of a connection, it is possible to
form a very efficient cooling arrangement such as is required by
thermally highly loaded internal combustion engines, for example
supercharged internal combustion engines, which are equipped with an
integrated exhaust manifold.

[0030] The cooling arrangement may reliably protect the internal
combustion engine, in particular the cylinder head 12, against thermal
overloading, and may preferably be efficient enough that an enrichment
(λ<1) at high exhaust-gas temperatures can be dispensed with.
During the course of an enrichment, more fuel is injected than can
actually be burned with the provided air quantity, with the additional
fuel likewise being heated and evaporated, such that the temperature of
the combustion gases falls. Said approach is however considered to be
disadvantageous from energy-related aspects, in particular with regard to
the fuel consumption of the internal combustion engine 10, and with
regard to pollutant emissions. In particular, the enrichment does not
always make it possible to operate the internal combustion engine 10 in
such a way as would be required for example for a provided exhaust-gas
aftertreatment system.

[0031] This configuration or design of the liquid cooling arrangement
makes it possible for the inlet side on the one hand and the outlet side
on the other hand to be cooled as required, specifically independently of
one another and according to the respective demand profile.

[0032] According to the present disclosure, the at least one coolant
jacket 56 of one circuit is arranged at the outlet side and the at least
one coolant jacket 54 of the other circuit is arranged at the inlet side,
such that different cooling capacities can be realized for the inlet side
and the outlet side, specifically not only through the use of different
coolants. Moreover, the pump power of each circuit, and therefore also
the coolant throughput, that is to say the feed volume, can be selected
and set independently of one another. In this way, it is possible to
influence the throughflow speed, which significantly co-determines the
heat transfer by convection.

[0033] In this way, it is possible for less heat to be extracted from the
cylinder head 12 at the inlet side and more heat to be extracted from the
cylinder head 12 at the outlet side.

[0034] In particular, the internal combustion engine 10 according to the
disclosure permits the use of oil as coolant for the inlet side in an oil
circuit 60 and the use of water as coolant in a water circuit 62 for the
thermally more highly or highly loaded outlet side of the cylinder head
12. In this embodiment, the cooling water circuit 62 does not comprise an
inlet-side coolant jacket. That is to say, the inlet side of the cylinder
head 12 is exclusively oil cooled, for which reason the heat is not
dissipated unused with the cooling water. Conversely, the oil circuit 60
may not comprise an outlet-side coolant jacket.

[0035] Oil has a lower heat capacity than water, as a result of which the
cooling capacity at the inlet side can be reduced noticeably in relation
to the use of water as coolant. This configuration of the liquid cooling
arrangement makes it possible for heat to be extracted from the cylinder
head 12 at the inlet side to the extent actually required to prevent
overheating. In contrast, in previous systems, on account of the uniform
use of water as coolant, the inlet side is cooled more intensely than is
actually required, because the cooling arrangement is designed with
regard to the thermally more highly loaded outlet side. The internal
combustion engine 10 according to the disclosure is therefore optimized
with regard to cooling. The efficiency of the internal combustion engine
10 is increased by the liquid cooling arrangement according to the
disclosure.

[0036] Furthermore, the use of oil as coolant for the at least one
inlet-side coolant jacket 54 has a further advantage. If the inlet-side
coolant jacket 54 jointly forms the oil circuit 60 of the internal
combustion engine, which oil circuit 60 supplies oil to consumers via a
supply line 52, the engine oil is heated up more quickly after a cold
start.

[0037] The oil specifically then flows, as it passes the cylinder head 12,
through the inlet-side coolant jacket 54, the most innate function of
which is the presently desired heat transfer. Here, the inlet-side
coolant jacket 54 is utilized for heating the oil during the warm-up
phase, and corresponding to its original function, for cooling the
cylinder head 12 when the internal combustion engine 10 has warmed up. In
both cases, the inlet-side coolant jacket 54 serves for introducing heat
into the oil.

[0038] While the heat which is introduced into the coolant at the inlet
side after a cold start advantageously ensures fast heating of the oil,
and therefore improves the operation of the internal combustion engine
10. The heat which, in previous systems, is introduced into the cooling
water serving as coolant is dissipated unused. The latter heat transfer
even counteracts a fast heating of the oil. The heating of the oil during
the warm-up phase is slowed here because a warm-up of the internal
combustion engine, and therefore also heating of the oil as it passes the
cylinder head or cylinder block, is counteracted.

[0039] With regard to the heating of the oil during the warm-up phase, the
inlet-side coolant jacket 54 has out of principle proven to be extremely
suitable. Firstly, the inlet-side coolant jacket 54 has an expanded
volume region to provide a large surface area, in particular in
comparison with an oil supply line, which has a relatively small surface
area. The expanded volume region may extend from an area adjacent to the
intake passage 24 down to the assembly end side of the cylinder head 12,
and may substantially surround an area around an intake passage port.
This increased surface area increases the heat transfer by convection.
Secondly, the cylinder head 12 into which the coolant jacket 54 is
integrated is thermally particularly highly loaded, which promotes the
introduction of heat into the engine oil during the warm-up phase on
account of the comparatively large temperature difference or temperature
gradient.

[0040] Therefore, for the reasons stated above, embodiments of the
internal combustion engine are particularly advantageous in which the at
least one outlet-side coolant jacket 56 belongs to a cooling water
circuit 62, whereas the at least one inlet-side coolant jacket 54 belongs
to an oil circuit 60. The two coolant circuits, specifically the cooling
water circuit 62 on the one hand and the cooling oil circuit 60 on the
other hand, are separate from one another.

[0041] Thus, the oil circuit 60 comprises the oil pan 48, which provides
oil to the oil pump. The supply line 52, upstream of the main oil gallery
64, leads through the cylinder head 12, preferably through the inlet-side
coolant jacket 54 of the cylinder head 12. The supply line 52 of the oil
circuit 60 firstly leads through the cylinder head 12 before said supply
line 52 enters into the cylinder block 14. The supply line 52 opens out,
downstream, into the main oil gallery 64.

[0042] In the oil circuit 60, the oil is heated in the cylinder head 12
and then is it used for lubricating engine components, such as the
bearings 46 of the crankshaft 22. While it is the case in the systems
described previously that the engine oil flows from the main oil gallery
to the cylinder head, in the present case, said oil is conducted from the
cylinder head 12 to the main oil gallery 64, which reduces the friction
in the bearings and reduces fuel consumption.

[0043] To supply the camshafts 36, 38 with oil, the supply line 52 may
further lead from the inlet-side coolant jacket 54 to the camshafts 36,
38.

[0044] This embodiment makes use of the fact that the cylinder head 12 is
thermally highly loaded, in particular is thermally more highly loaded
than the cylinder block 14, such that the heating of the oil, that is to
say the rise in the oil temperature, as said oil flows through the
cylinder head 12 is more pronounced than when said oil flows through the
cylinder block 14.

[0045] After a cold start, the cylinder head 12 warms up more quickly, in
particular in relation to the cylinder block 14, as a result of the
combustion processes taking place. The embodiment in FIG. 1 ensures that
the crankshaft bearings 46 are supplied with pre-heated oil more quickly,
and in particular prevents a situation in which the oil entering into the
cylinder head 12 has heat extracted from it upstream in the cylinder
block 14.

[0046] In another embodiment, depicted in FIG. 2, the supply line 52 may
lead firstly through the cylinder block 14 and subsequently, that is to
say downstream, through the cylinder head 12, preferably through the
inlet-side coolant jacket 54.

[0047] In addition to the coolant jackets 54, 56, 58 arranged in the
cylinder head 12, in some embodiments, the cylinder block 14 may include
cooling jackets. In addition to the cylinder head 12, the cylinder block
14 is also a thermally highly loaded component, such that the cylinder
block 14 may also be equipped with one or more coolant jackets in order
to form a liquid cooling arrangement. This may be advantageous in
particular if it is sought to use less temperature-resistant materials,
or in supercharged internal combustion engines, which are thermally more
highly loaded than naturally-aspirated engines.

[0048] The cylinder block 14 may comprise an outlet-side coolant jacket 57
on the outlet side as part of the cooling water circuit 62. The coolant
jacket 57 of the cylinder block 14 may be arranged upstream of the at
least one coolant jacket 56 of the cylinder head 12, or it may be
arranged downstream. In other embodiments, the cylinder block 14 may
comprise an inlet-side coolant jacket 55 as part of the oil circuit 60.
The coolant jacket 55 of the cylinder block 14 may be arranged upstream
of the at least one coolant jacket 54 of the cylinder head 12, or it may
be arranged downstream. In some embodiments, the cylinder block may
comprise both coolant jackets 55, 57. The arrangement of the cylinder
block 14 and head 12 or flow direction of the coolant is dependent on the
individual situation, in particular also on what coolant is used and what
cooling circuit the coolant jacket of the block 14 belongs to.

[0049] Turning to FIG. 3, the engine 10 described with reference to FIG. 1
is depicted. Here, all cylinders of engine 10 are shown. In addition to
cylinder 16, cylinders 66, 67 are depicted. While engine 10 is here
depicted as a three-cylinder engine, it is to be understood that any
number of cylinders in any arrangement is within the scope of this
disclosure.

[0050] An intake manifold 68 provides intake air to the cylinders via
intake passages, such as intake passage 24. After combustion, exhaust
gasses exit the cylinders via exhaust passages, such as exhaust passage
26, to the exhaust manifold 70. The exhaust lines of at least two
cylinders may be merged to form an overall exhaust line within the
cylinder head, so as to form an integrated exhaust manifold that permits
the densest possible packaging of the drive unit. In some embodiments,
the exhaust lines of the at least two outlet openings of each cylinder
are merged to form a partial exhaust line associated with the cylinder,
before the partial exhaust lines of at least two cylinders are merged to
form an overall exhaust line. The exhaust gasses may pass through one or
more aftertreatment devices (not shown) before exiting to the atmosphere.

[0051] The overall length of all the exhaust lines is further shortened in
this way. The stepped merging of the exhaust lines to form an overall
exhaust line also contributes to a more compact, that is to say less
voluminous design of the cylinder head, and therefore in particular to a
weight reduction and more effective packaging in the engine bay.

[0052] In the case of an integrated manifold, the at least one connection
described in reference to FIG. 1 and illustrated in FIG. 4 is preferably
arranged adjacent to the region in which the exhaust lines merge to form
an overall exhaust line, with the spacing between the at least one
connection and the overall exhaust line preferably being smaller than the
diameter or radius of a cylinder. The spacing is defined as the distance
between the outer wall of the overall exhaust line and the outer wall of
the connection.

[0053] The engine 10 may be supercharged by means of an exhaust-gas
turbocharger. The exhaust gas may pass through a turbine 72 to drive a
compressor 74 to provide boosted intake air to engine 10.

[0054] Here, it is sought firstly to arrange the turbine 72 as close as
possible to an outlet of the internal combustion engine 10 in order
thereby to be able to optimally utilize the exhaust-gas enthalpy of the
hot exhaust gases and to ensure a fast response behavior of the
turbocharger. Secondly, the path of the hot exhaust gases to the
different exhaust-gas aftertreatment systems may also be as short as
possible such that the exhaust gases are given little time to cool down
and the exhaust-gas aftertreatment systems reach their operating
temperature or light-off temperature as quickly as possible, in
particular after a cold start of the internal combustion engine.

[0055]FIG. 4 shows a slightly inclined plan view of sand cores 102, 104
used to form cooling jackets, e.g. the coolant jackets 54, 56 discussed
with regard to FIG. 1, of two coolant circuits which are separate from
one another, such as are integrated, according to a first embodiment, in
the cylinder head 12 of the internal combustion engine 10.

[0056] The sand cores 102, 104 shown here are those of a three-cylinder
in-line engine, such as engine 10, in which each cylinder has, at the
outlet side, two outlet openings for discharging the exhaust gases out of
the cylinders, and at the inlet side, two inlet openings for the supply
of fresh air to the cylinders, with an exhaust line being connected to
each outlet opening and an intake line being connected to each inlet
opening. The exhaust lines of the three cylinders merge to form an
overall exhaust line within the cylinder head, so as to form an
integrated exhaust manifold.

[0057] In FIG. 4, the inlet-side sand core 104, which forms the inlet side
coolant jacket of the oil circuit, is arranged between the assembly end
side and the intake lines. The outlet-side sand core 102, which forms two
outlet-side coolant jackets of the water circuit, comprises a lower sand
core 108 and an upper sand core 110, of which a lower sand core 108 is
arranged between the assembly end side and the integrated exhaust
manifold, and an upper sand core 110 is arranged on that side of the
exhaust manifold which is situated opposite the lower sand core 108.
Consequently, the manifold is situated between the lower coolant jacket
and the upper coolant jacket and is encased by said coolant jackets over
a large area. The cooling water circuit does not comprise an inlet-side
coolant jacket. On that side of the exhaust manifold which faces away
from the cylinders and on which the overall exhaust line also emerges out
of the cylinder head, two connections 112 are provided between the lower
sand core 108 and the upper sand core 110, which connections serve to
permit the passage of cooling water, wherein one connection 112 is
visible in the plan view of FIG. 3.

[0058] The two connections 112 are arranged adjacent to the overall
exhaust line, that is to say to that region of the manifold at which the
exhaust lines merge and the cylinder head is thermally particularly
highly loaded.

[0059] To remove the sand cores 102, 104 after the casting of the cylinder
head, access ports 114, 116, 118 are provided which also serve as sand
core supports during the casting process. The access ports 114, 116, 118
are closed off after the casting process. Such access ports 114, 116, 118
may however fundamentally also be used within the context of the liquid
cooling for the supply and discharge of coolant to and from the coolant
jackets or circuits.

[0060] The access ports 114, 116 are provided in the region of the two
connections 112, via which the lower sand core 108 and the upper sand
core 110 communicate with one another.

[0061] In the embodiment illustrated in FIG. 4, cooling water inlets 120
and cooling oil inlets 122 are formed on the side facing toward the
assembly end side, which inlets are aligned substantially parallel to the
cylinder longitudinal axes. In contrast, the associated coolant outlets
124, 126 run substantially parallel to the crankshaft longitudinal axis.
A ventilation line 128 serves to ventilate the cooling water circuit.

[0062]FIG. 5 shows a side view of the sand cores 102, 104 illustrated in
FIG. 4, with a view in the direction of the crankshaft longitudinal axis.
It is sought merely to explain the additional features in relation to
FIG. 4, for which reason reference is made otherwise to FIG. 4. The same
reference signs are used for the same components.

[0063] It can be seen from FIG. 5 that, on the side facing toward the
assembly end side, two cooling water inlets 120, 130 enter into the lower
sand core 108 of the cooling water circuit, and two cooling oil inlets
122, 132 enter into the inlet-side sand core 104 of the oil circuit, and
that the inlets 120, 130, 122, 132 run substantially parallel to the
cylinder longitudinal axes.

[0064] It can be clearly seen that the lower and the upper sand cores 108,
110 are not connected to one another over the entire length of the
manifold which is encased by them. The ventilation line 128 runs in the
uppermost section of the cooling water circuit.

[0065] FIG. 6 is a flow chart illustrating a method 200 for cooling an
engine. Method 200 comprises, at 202, cooling an outlet side of a
cylinder via a water circuit. Cooling the outlet side of the cylinder
further comprises, at 204, routing water to a first coolant jacket, such
as coolant jacket 56, and, at 206, routing water to a third coolant
jacket, such as coolant jacket 58. The first and third coolant jackets
are arranged on the outlet side of the cylinder.

[0066] Method 200 comprises, at 208, cooling at inlet side of a cylinder
via an oil circuit. Cooling the inlet side of the cylinder further
comprises, at 210, routing oil to a second coolant jacket arranged on an
inlet side of the cylinder, such as coolant jacket 54. At 212, oil is
pumped from an oil pan to the second coolant jacket. At 214, method 200
comprises routing oil from the second coolant jacket to oil consumers via
a main oil gallery.

[0067] It should be understand that the above described method is not
intended to be carried out in a specific order. For example, cooling the
outlet side of the cylinder and cooling the inlet side of the cylinder
may occur simultaneously, by routing the water to the outlet side coolant
jacket at the same as the oil is routed to the inlet side coolant jacket.

[0068] Thus, the systems and methods presented here may provide several
advantages. By directing oil through an inlet-side coolant jacket, the
oil may be quickly heated while maintaining an appropriate amount of
cooling to the inlet side of a cylinder. Heated oil, or oil at a
relatively high temperature, has a relatively low viscosity, which
reduces the friction losses of the internal combustion engine and
improves the efficiency. As a result, the fuel consumption of the
internal combustion engine is noticeably reduced by the heating of the
oil, in particular after a cold start.

[0069] The significant advantage of the approach described herein over
concepts in which the oil is actively heated by means of a heating device
lies in the comparatively simple design of the oil heating facility
according to the disclosure. Basically no additional components are
required, in particular no external heating device. The lack of a heating
device also eliminates the additional fuel consumption generated by such
a device. According to the disclosure, a coolant jacket provided to form
a liquid cooling arrangement is assigned to an already existing oil
circuit in order to be able to heat up the oil more quickly during a
warm-up.

[0070] Further, the cooling of the outlet side of the cylinder head may
additionally and advantageously be improved by virtue of a pressure
gradient being generated between the upper and lower coolant jackets, as
a result of which the speed in the at least one connection is increased,
which leads to an increased heat transfer as a result of convection.

[0071] Here, the lower and upper coolant jackets may be connected to one
another over their entire width or else in sections, that is to say over
a partial region of the coolant jackets. In this way, it is possible to
influence the flow speed in the at least one connection and therefore the
heat transfer by convection.

[0072] It is to be understood that various steps or functions illustrated
in the disclosure may be performed in the sequence illustrated, in
parallel, or in some cases omitted. Likewise, the order of processing is
not necessarily required to achieve the objects, features, and advantages
described herein, but is provided for ease of illustration and
description. Although not explicitly illustrated, one of ordinary skill
in the art will recognize that one or more of the illustrated steps or
functions may be repeatedly performed depending on the particular
strategy being used.

[0073] This concludes the description. The reading of it by those skilled
in the art would bring to mind many alterations and modifications without
departing from the spirit and the scope of the description. For example,
I3, I4, I5, V6, V8, V10, and V12 engines operating in natural gas,
gasoline, diesel, or alternative fuel configurations could use the
present description to advantage.